Synthesis of some 2,4‐disubstituted tetrahydropyrimido[4,5‐ b ]quinolines as potential antitumor agents

Cyclocondensations of two 2,4‐disubstituted 6‐aminopyrimidines with 2‐chloro‐1‐cyclohexenecarboxaldehyde afforded in each case a new regiospecific synthesis of tricyclic, linear disubstituted 6,7,8,9‐tetrahydro‐pyrimido[4,5‐ b ]quinolines 2 and 3 in excellent yields. The linear structures and hence the regiospecificity of the synthesis were established using 1 H nmr and 13 C nmr. The growth of leukemia L1210 cells in culture was inhibited 50% by 2 at 30 × 10 −6 M and 48% by 3 at 100 × 10 −6 M.